An integrated assessment of the financial and environmental impacts of exterior building insulation application

Abstract

In the literature, optimum thermal insulation thickness on building's exterior was examined by many researchers. Optimum insulation thickness was generally studied with the aim of minimizing the total cost, and suitable values were determined within this scope. In this study, it has also considered the amount of CO2 released into the atmosphere due to the fuels used in building heating and cooling processes, as well as insulation materials, in addition to the total cost. This study has been focused on optimization of the determination of the ideal insulation thickness of buildings by simultaneously minimizing the total cost and CO2 emission, using the knee point approach. In this context, a multi-objective optimization study has been conducted for thermal insulation applied to buildings located in different climatic zones considering the solar radiation. A comprehensive analysis has been carried out to determine the impact of the heating source type (natural gas, electricity, fuel oil), insulation material (expanded polystyrene, extruded polystyrene, mineral wool, polyurethane foam), climatic zone (I, II, III, IV) and the purpose of the building's use (summer house, winter house or all-season house) on the optimum insulation thickness. The degree-day approach has been used to calculate annual energy consumption, and accordingly the life-cycle cost (LCC) method has been used in economic analysis. The optimum insulation thicknesses have been calculated with two separate objectives: one to minimize only the total cost and the other to minimize only the CO2 emissions. It has been found that when the primary goal of insulation application is to minimize CO2 emissions, the calculated optimum insulation thicknesses are consistently higher compared to situations where the main goal is minimizing total cost. Furthermore, for various climatic zones and different purpose of the building's use, an ideal insulation thicknesses that simultaneously minimizes both the cost and CO2 emissions have been identified. In this research, the equations providing environmentally optimum insulation thicknesses to minimize CO2 emissions have been derived and presented to researchers. Finally, the conclusion is drawn that the knee point approach can be applied in insulation scenarios where two objective functions need simultaneous optimization.